This invention relates to a charged particle beam lithography system for use in a lithography process for manufacture of semiconductor devices and more particularly to a charged particle beam lithography system having a system configuration suitable for achieving cost reduction and high throughput.
The charged particle beam lithography system ma be classified into two types of which one uses an electron beam and the other uses an ion beam, and will conveniently be described herein by way of example of the former type.
Lithography techniques can not well comply with the recent trend toward high-density, fine semiconductor devices, without resort to an electron beam direct lithography in which an electron beam is finely focused on a wafer coated with resist so as to draw a pattern directly on the wafer. The electron beam direct lithography can fully fulfill itself in the formation of fine patterns but disadvantageously, it has a small throughput and can not therefore be practiced in the device production line on mass production basis.
In order to increase the working speed of the electron beam lithography system, many advanced elemental techniques have been developed, including an expedient for speed-up of the control circuit system described in, for example, "A high speed, high precision electron beam lithography system" by K. Nakamura et al., J. Vac. Sci. Technol., B3(1), p. 94, Jan/Feb, 1985 and an approach to a continuous stage movement system for variable shaped beam electron optics described in, for example, "An electron beam lithography system for submicron VHSIC device fabrication" by H. J. King et al., J. Vac. Sci. Technol., B3(1), p. 106, Jan/Feb, 1985.
However, even with the best combination of these elemental techniques, if the conventional system configuration in which one control circuit system controls one channel of an electron beam system is adhered to, then the throughput per channel will be technically limited and estimated to be 20 to 30 sheets/hour at the most for a wafer of 4 to 5 inches. Further, the lithography system is very costly in terms of one channel and can not be manufactured commercially with profitability.